Synthesis of Azoxy Dyes and Their Copper Complexes and Their Application on Polyvinyl Alcohol (PVA) Polarizing Film

Azoxy dyes and their copper complexes with maximum dichroism in the spectrum range from 550nm to 700nm were synthesized and used to prepare polyvinyl alcohol (PVA) polarizing films. These films showed excellent polarizing ability. In addition, a neutral gray polarizing film was prepared by mixing synthesized dichromatic dyes with other dyes. The obtained polarizable film for gray shade was little pervious to light over the visible radiation wavelength region, ranging from 400nm to 700nm at cross state, and excellent in the polarizing activities and stable to moisture and heat.

Characterization of Passive Film Formed on 304 SS in Simulated Alkaline Water Chemistries Containing Sulfur at 300℃

Passivity degradation of 304 stainless steel(SS) in simulated alkaline water chemistries at 300℃ was investigated using polarization curve, scanning electron microscope, time-of-flight secondary ion mass spectrometry(SIMS) and X-ray photoelectron spectroscopy(XPS). Experimental results indicated that 304,SS was selfpassive in the test solution and the thickness of passive film was about 500 nm. Hydroxide was enriched in the outer layer whereas oxide was enriched in the inner layer. Sulfur in thiosulfate could be reduced into lower valence of sulfur and enter the passive film so that the composition of passive film was modified by sulfur. Fe and Cr were enriched in the passive film whereas Ni was depleted in the passive film.

Analysis of properties of krypton ion-implanted Zn-polar ZnO thin films

The optical properties of materials are of great significance for their device applications.Different numbers of krypton ions are doped into high-quality Zn-polar ZnO films fabricated by molecular beam epitaxy(MBE)on sapphire substrates through ion implantation.Krypton is chemically inert.The structures,morphologies,and optical properties of films are measured.The x-ray diffraction(XRD)spectra confirm the wurtzite structures of Zn-polar ZnO films.Atomic force microscopy(AFM)results show that the films have pit surface structure and higher roughness after Kr ion implantation.A detailed investigation of the optical properties is performed by using the absorption spectrum,photoluminescence(PL),and spectroscopic ellipsometry(SE).The absorption spectrum is measured by UV-visible spectrophotometer and the bandgap energy is estimated by the Tauc method.The results show that the absorption increases and the bandgap decreases after Kr ion implantation.Moreover,the Kr ion implantation concentration also affects the properties of the film.The ellipsometry results show that the films'refractive index decreases with the Kr ion implantation concentration increasing.These results can conduce to the design and optimization of Kr ion-implanted polar ZnO films for optoelectronic applications.

Improved Polarization Retention of BiFeO3 Thin Films Using GdScO3(110)Substrates

Epitaxial ferroelectric one direction over the thin fihns on single-crystal substrates generally show a preferred domain orientation in other in demonstration of a poor polarization retention. This behavior will affect their application in nonvolatile ferroelectric random access memories where bipolar polarization states are used to store the logic 0 and 1 data. Here the retention characteristics of BiFe03 thin films with Srftu03 bottom electrodes on both GdSc03 （110） and SrTiO3 （100） substrates are studied and compared, and the results of piezoresponse force microscopy provide a long time retention property of the films on two substrates. It is found that bismuth ferrite thin films grown on GdScO3 substrates show no preferred domain variants in comparison with the preferred downward polarization orientation toward bottom electrodes on SrTi03 substrates. Tile retention test from a positive-up domain to a negative-down domain using a signal generator and an oscilloscope coincidentally shows bistable polarization states on the GdSeOa substrate over a measuring time of 500s, unlike the preferred domain orientation on SrTi03, where more than 65~o of upward domains disappear after 1 s. In addition, different sizes of domains have been written and read by using the scanning tip of piezoresponse force microscopy, where the polarization can stabilize over one month. This study paves one route to improve the polarization retention property through the optimization of the lattice-mismatched stresses between films and substrates.

Enhanced Ferroelectric Polarization in Laser-ablated Bi4Ti3O12 Thin Films by Controlling Preferred Orientation

Polycrystalline Bi_4Ti_3O_（12） thin films with various fractions of a-axis, c-axis and random orientations have been grown on Pt（111）/Ti/Si O_2/Si substrates by laser-ablation under different kinetic growth conditions. The relationship between the structure and ferroelectric property of the films was investigated, so as to explore the possibility of enhancing ferroelectric polarization by controlling the preferred orientation. The structural characterization indicated that the large growth rate and high oxygen background pressure were both favorable for the growth of non-c-axis oriented grains in the Bi_4Ti_3O_（12） thin films. The films with high fractions of a-axis and random orientations, i e, f（a-sxis） = 28.3% and f（random） = 69.6%, could be obtained at the deposition temperature of 973 K, oxygen partial pressure of 15 Pa and laser fluence of 4.6 J/cm^2, respectively. It was also noted that the variation of ferroelectric polarization was in accordance with the evolution non-c-axis orientation. A large value of remanent polarization（2 Pr = 35.5 μC/cm^2） was obtained for the Bi_4Ti_3O_（12） thin films with significant non-c-axis orientation, even higher than that of rare-earth-doped Bi_4Ti_3O_（12） films.

Enhancement of second-order harmonic generation in polarized BaTiO_3 thin films embedded with Ag nanoparticles

RECENTLY, much attention has been paid to optical properties of ferroelectric thin films. Be-

Terahertz broadband polarizer using bilayer subwavelength metal wire-grid structure on polyimide film

A tcrahcrtz （THz） broadband polarizer using bilayer subwavelength metal wire-grid structure on both sides of polyimide fihn is simulated by the finite-difference time-domain method. We amdyze tile effect of film thickness, material loss, and lateral shift between two metallic gratings on the performance of the THz polarizer. Bilayer wire-grid polarizers are fabricated by a simple way of laser induced and non-electrolytic plating with copper. The THz time-domain spectroscopy measurements show that in 0.2 1.6 THz frequency range, the extinction ratio is better than 45 dB, the average extinction ratio reaches 53 dB, and the transmittance exceeds 67%, which shows great advantage over conventional single wire-grid THz polarizer.

Corrosion Evolution of Low Alloy Steel in Deaerated Bicarbonate Solutions

Corrosion evolution during immersion tests （up to 43 days） of NiCu steel in deaerated 0.1 mol/L bicarbonate solutions was investigated by electrochemical measurements, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Results show that NiCu steel transformed from the anodic dissolution in the early stage of immersion to a metastable passive state in the final stage as the open-circuit potential value shifted positively, which was aroused by the precipitation of corrosion products. This process was mainly promoted by the trace amount of oxygen. Simultaneously, dominant cathodic reaction transformed from the hydrogen evolution in early stage to reduction processes of corrosion products in later stages. Possible corrosion processes were discussed with the assistance of a corresponding Pourbaix diagram.

Effect of solution pH,Cl- concentration and temperature on electrochemical behavior of PH13-8Mo steel in acidic environments

The effect of solution pH,Cl;concentration and temperature on the electrochemical corrosion behavior of PH13-8Mo steel in acidic solution was investigated by using the electrochemical tests,scanning electron microscopy and X-ray photoelectron spectroscopy.The PH13-8Mo martensitic precipitation hardened stainless steel is in the passivity state when the pH value is above 3.0,below which the anodic polarization curves of the steel are actively dissolved.The corrosion current density gradually decreases with increasing the solution pH and decreasing Cl;concentration and solution temperature.Pits are initiated on the sample surface in the presence of the Cl;and gradually developed into uniform corrosion with increasing the Cl;concentrations.Moreover,the corrosion is more serious with an increase in solution temperature.